According to the hydrophobic principle of the laws of nature, a system will always struggle towards lowest possible energy consumption. When two water repellent molecules come into collision with each other they will increase the entropy and create disorder. The water molecules that surround the two hydrophobic molecules will force them together by hydrogen bonds between the water molecules although there is no force of attraction between the hydrophobic molecules, and will expel the water molecules.
Numerous studies during the last few decades have shown that bacteria, the yeast Candida albicans and the fungus Trichophyton rubrum commonly express profound cell surface hydrophobicity. Several structures which render the cell surface hydrophobic have been defined, like the fimbriae of Escherichia coli which mediate adhesion to the intestinal wall, proteins on Candida albicans and T. rubrum which have been called “hydrophobins”, and lipoteichoic acid in the cell wall of Gram-positive bacteria.
The initial step of infections of the skin and mucosal surfaces is microbial adhesion to wounded tissues. Several microbial components that adhesively bind to specific receptors have been identified. Initial adhesion can be mediated by hydrophobic interactions between microbes and host tissue structures, and also by charge interactions. Binding of extracellular matrix and serum proteins, like fibronectin, collagen and fibrinogen may further enhance colonization of deeper wound tissue. Utilizing the SORBACT® principle described in patent application WO2006062470, assigned to the same group as the instant invention, products such as the SORBACT® pad consist of folded acetate gauze and cotton gauze treated with the fatty acid ester DACC (dialkyl carbamoyl chloride). This provides SORBACT® pads with a strong hydrophobic property. When the SORBACT® pad comes into contact with pathogenic microorganisms in the wound surface, the microorganisms adhere to the pad through hydrophobic interaction. The method is based on the principle that two hydrophobic surfaces bind to each other, when coming into physical contact. The SORBACT® pad consists of two components. The first component has one or more liquid permeable layers of a hydrophobic, bacteria-adsorbing, physiologically innocuous material containing a woven or nonwoven hydrophilic fabric. The fabric has been rendered hydrophobic by chemical treatment with a compound containing hydrophobic groups. The second component consists of one or more layers of a hydrophilic, liquid adsorbing, physiologically innocuous material. The hydrophilic liquid absorbing material affects a liquid flow by suction of exudate from the wound. If the microorganisms exhibit hydrophobic surface structures they will accompany this flow of liquid and come in contact with the hydrophobic component and bind to it.
Another antimicrobial property of the SORBACT® product is its cation activity. The exterior membranes of mammalian cell exterior membranes are generally neutral. Thus the positively charged SORBACT® material preferentially binds to membranes of microorganisms (negatively charged) and lifts them away. U.S. patent application Ser. No. 10/559,464 (publication number 2006/0163149) relates to a product for absorption, whereby a hydrophobic entity and a positively charged entity are connected to a support matrix. In this method, the hydrophobic entity may be connected by using DACC, and the positively charged entity may be connected by using polyethyleneimine. Preferred fields of the prior application are filters, face masks, wound dressings, nasal sprays, and drapes for use during surgical intervention etc. However unlike the invention herein they do not mention treatment of athlete's foot nor attachment of a hydrophobic material to foam or the like.
Athlete's foot is a common name given to a fungal infection of the skin that predominately occurs between the toes but can occur anywhere on the foot. The term athlete's foot is a highly misleading word, as this condition does not only occur in athletes. It is caused by one of four dermatophytes, the most common being Trichophyton rubrum, which is a microscopic fungus that lives on dead tissue of the hair, toenails, and outer skin layers. The fungus thrives in warm, moist environments including shoes, socks, and the floors of public showers, locker rooms, and swimming pools. Athlete's foot is transmitted through contact with a cut or abrasion on the plantar surface (bottom) of the foot. The infection causes raised, circular pimples or blisters.
There are four common forms of athlete's foot. The most common is a persistent itching of the skin on the sole of the foot or between the toes. As the infection progresses, the skin grows soft. The center of the infection is inflamed and sensitive to the touch. Gradually, the edges of the infected area become milky white and the skin begins to peel. There may also be a slight watery discharge.
The second presentation is the ulcerative type. In this presentation, the peeling skin becomes worse. Large cracks develop in the skin, making the patient susceptible to secondary bacterial infections. The infection can be transmitted to other parts of the body by scratching or contamination of clothing or bedding.
The third type of infection is often called “moccasin foot.” In this type, a red rash spreads across the lower portion of the foot in the pattern of a moccasin. The skin in this region gradually becomes dense, white, and scaly.
Finally, the fourth form of tinea pedis is inflammatory or vesicular, in which a series of raised bumps or ridges develops under the skin on the bottom of the foot, typically in the region of the metatarsal heads. Itching is intense and there is less peeling of the skin.
People with acute tinea infections may develop similar outbreaks on their hands, typically on the palms. This trichophyde reaction, also known as tineas manuum, is an immune system response to fungal antigens (antibodies that fight the fungal infection).
Tinea pedis has proven difficult to eliminate and often recurs. Infections may disappear spontaneously or persist for years. Best results usually are obtained with early treatment before the fungal infection establishes itself firmly. Historically, antifungal drugs have been used. For early “mild” cases, Imidazole class drugs are used to combat fungal infections by attacking the enzymes of the fungal cell walls, inhibiting growth and reproduction. Examples of these drugs include clotrimazole (LOTRIMIN®) and miconazole (contained in LOTRIMIN® and ABSORBINE JR.®). They are applied topically and massaged into the skin. They must be reapplied every few hours over a period of weeks.
More difficult cases may require the use of the allylamines class of drugs. These drugs include terbinafine (contained in LAMISIL®) and naftifine (NAFTIN®) and are available in non-prescription form. The most difficult cases must be treated with drugs such as griseofulvin (FULVICIN® and GRISACTIN®) and concentrated forms of terbinafine and itraconazole. Griseofulvin can cause side effects such as headache, nausea, and numbness, so it is used as a last resort.
These treatments are not without shortcomings. The topical treatments require use for many days, if not weeks. Often the condition occurs on the skin areas of the feet that that come into frequent frictional contact with a patient's clothing or with other skin surfaces. As a result of this frictional contact, topically applied medications can be more easily removed from the affected areas of a patient's foot. Moreover, topically applied medications are more prone to the effects of moisture that is present at the affected area of skin. These difficulties mean that treatment is significantly reduced, because the medication is not held in place for a sufficient time. As a result, the efficacy of the treatment is significantly reduced, and patients must frequently reapply medications so that the affected area receives proper treatment. Furthermore, the inconvenience of bandages due to constant or frequent movement and flexing of the skin, the small surface area usually involved (such as the toes), friction and moisture, make bandages impractical for minimizing frictional contact that occurs at the affected areas of a patient's foot, as well as impractical as a means to hold the medication in place for longer periods of time. In other words, the topical medications are messy creams and lotions. When it comes to internal drugs, the issue is that they can cause side effects, including headaches, nausea, and in extreme cases, organ damage.
Patches for treatment of athlete's foot are not previously described in literature while band-aids for the treatment of toe and finger nail fungus infections are known, for instance, WO-A-99/40955, U.S. Pat. No. 5,753,256 and US patent applications US20040265362, US20040161452 and U.S. Pat. No. 5,464,610.
The invention described in US patent application 20030068331 relates to gum resin or other film forming agent-based biological dressings that adhere to the skin and contain one or more pharmacologically active agents for the treatment of symptoms relating to athletes foot. The biological dressing comprises a sticky film of gum resin or other agent which forms a film on the skin and a pharmacologically active agent. This is in contrast to the invention herein where the dressing is ring-shaped or dog-bone shaped, non-sticky and removable. Furthermore the invention herein does not comprise any pharmacologically active agents, since the efficacy is due to hydrophobic action in combination with the separation of toes.
There are many different types of toe separators commercially available from foot care manufacturers. These are usually made of variously shaped pieces of soft silicon, felt or foam material that may be impregnated with soothing oils or aromatic substances. These are placed separately between the toes that chafe each other to prevent the interdigital fiction. They can be ring-shaped as in the invention herein but the toe separators are only used for separation of the toes. They only get the drying effect and not both the drying and the removal of the fungus.
Circular cushions are known for placement over calluses, for example “Round Callus Cushions”, sold by DR. SCHOLL'S®. Unlike the invention herein such cushions are not mounted with foam material with a hydrophobic fabric attached thereto, nor are they meant to be placed around a toe.
There are a number of patents and patent applications describing drying appliances for preventing athlete's foot e.g, DE 10020989, U.S. Pat. No. 3,943,922 A, and U.S. Pat. No. 5,497,789. However unlike the invention herein the anti-fungal effect is due to drying between the toes by separators not due to elimination of microbes by the hydrophobic effect.
Patent application WO2004017881 discloses a moisture-absorbing soft sleeve to be passed on the toe for treating athlete's foot. The sleeve is made of wood or cotton. The disadvantage of the invention is that the sleeve is only efficient when dry. Under moisture conditions, unfortunately, the microbes are able to multiply.
Therefore, there is a need for an alternative athlete's foot treatment without using antimicrobial substances, that due to a perfect fit remains at the treatment site for a sufficient period, that reduces the spread or transmission of the fungal infection, and that provides fast, effective relief from the symptoms of athlete's foot.
The inventors herein surprisingly discovered that a ring-formed toe-patch consisting of a hydrophobic material with a foam-layer described in patent application US2008/0177214 met this need. The invention is not limited to just a ring-formed product but relates to all toe-patches consisting of a hydrophobic material with a foam-layer cut to have a perfect fit around a tinea pedis affected area, for example dogbone-shaped toe-patches.
Due to the perfect fit the product of the invention herein can come close to the affected area for an effective treatment. Simultaneously with the elimination of the fungus it works as a toe separator creating space between the toes, so that the attacked area will be aired and dried up. The use of the moisture-absorbent foam attached to the hydrophobic material increase the drying effect. This material was disclosed by the inventors of the invention herein and described in US 2008/0177214. In contrast to the topically applied medications on the market that are more prone to the effects of moisture the invention herein provides a significantly more effective treatment of athlete's foot.
The product is held on place by normal socks and may be used together with ordinary footwear. Accordingly, the patient can be spared of the inconvenience of bandages due to movement, friction and moisture.
Furthermore, because the treatment and prevention methods of the present invention provide a stronger physical barrier at the affected skin area, the risks of spread or transmission of the fungal infection, either to other areas of the patient's body or to other individuals is significantly decreased. The present invention thus provides significant public health benefits.